Sensibly equivalent¶ to:
This exhibit is an early DER triode. The thoriated tungsten filament and the planned use in receiving gave the valve its name - Dull Emitting Receiving.
Visual inspection shows that the anode cylinder of this valve is vertical within the envelope and this was the earliest form of the DER construction. However, the electrodes were prone to vibration and the valve thus became microphonic. To remove this problem the traditional horizontal construction was used for later production.
The balloon envelope is 48 mm in diameter and, excluding the B4 base pins, is 100 mm tall.
Reference: 1003. Type DER was first introduced in 1921.
Absolute Maximum Operating Conditions¶
Updated July 31, 2015.